Abstract:Fairness and inequity aversion are two sides of one coin. Inequity aversion is beneficial for the establishment and maintaining of the fairness norm. Inequity aversion means the urge to allocate resources equally as a distributor and the willingness to sacrifice self-interest to move in the direction of a more equitable division as a responder. However, children’s performance between these two characters has not been systematically compared. In addition, children’s inequity aversion to procedures remains largely unknown. The present research focused on children’s inequity aversion to unfair distribution and procedure when acting as proposers and responders. We found children performed differently as a distributor and a responder. Children at the age of 4 started to distribute resources equally. When equal distribution is impossible, children at 4 showed a preference toward equal procedures to decide who get the bigger reward, but only when the alternative procedure was disadvantageous to them. When the alternative was advantageous, it was until 8 years old that children started to show inequity aversion. As a responder, on the other hand, children aged 6 began to reject both advantageous and disadvantageous unequal offers. However, it was until 8 years old when children were more likely to reject outcomes generated through unfair procedures. Our results suggested that children are more likely to show their inequity aversion when distributing resources. Moreover, compared with outcomes, children’s inequity aversion to unfair procedures develops at a later age.